1. Field
The present invention relates to apparatus and methods for producing crude oil having poor flowability from subterranean formations.
2. State of the Art
Crude oil is produced by conducting it from subterranean formations through wells to the surface. A commonly observed phenomenon in the production of crude oil is the deposition of paraffin onto the walls of production tubing or the wellbore. Such deposition reduces the cross-sectional area of the conductive pathway thereby restricting the flow of the crude oil.
One way of dealing with this problem has been to pump hot fluid down the well so as to dissolve the paraffin and reopen the conductive pathway of the well. However, such an operation is expensive. Heating the fluid consumes considerable energy and much manpower is expended in operating the system.
Electro-thermal paper is a thin, highly flexible sheet material for low-cost electrical resistance heating that has been available for some time. Electro-thermal paper has several advantages. It can produce heat over an area of any size and configuration. Because it contains no wires or metal in the material, it is free of localized hot spots and consequent breakage problems. It can also be bent around a 1/4inch radius with little effect on its electrical properties. The type of paper used and the method of its manufacture is disclosed in U.S. Pat. Nos. 3,781,526 and 4,374,312 both to Damron.
The paper is also relatively durable depending on the temperature at which it is used. At 150 degrees Fahrenheit, for example, its stability is measured in tens of years. At 200 degrees Fahrenheit, its stability is measured in months. Heretofore, so far as is known by applicant, no one has applied electro-thermal paper technology to oil well production and to the problem o paraffin deposition.